On average one bit per subcarrier channel state information feedback in OFDM wireless communication systems

In the orthogonal frequency division multiplexing (OFDM) scheme, some subcarriers may be subject to a deep fading. Adaptive techniques can be applied to mitigate this effect if the channel state information (CSI) is available at the transmitter. In this paper, we study the performance of an OFDM-based communication system whose transmitter has only one bit (of CSI per subcarrier that is obtained through a low rate feedback. Three adaptive approaches are considered to exploit such a CSI feedback: adaptive subcarrier selection, adaptive power allocation and adaptive modulation selection. Under the condition of constant raw data rate, the performance of these approaches is analyzed and compared in terms of raw bit error rate (BER). We have found that one-bit CSI feedback can greatly enhance the system performance. Among the three approaches, the adaptive subcarrier selection approach is found to have the lowest BER when the feedback is perfect.